Make a switch. Turn the switch on and it shall not happen again as long as it is on. Here is what I mean, in simpler terms:
1)Open up the event.
2) find the place where the even ends (in the white box) and click there. In the event commands list stay on the first page and click "Switch Operations"
3)Leave everything that appears now as normal, just go and click the small "..." next to the long white box.
4) pick a spot, name it, and then hit "OK".
5) NOW..while still in the event editor, go and make a new page (by hitting the "New Page"
button at the top.
6) Now when your on the new page, look to the left and it says "Preconditions" at the top with the words:
Switch_________
Switch_________
Item_________
Variable_______
etc.
7)On the first "Switch" option tik the little white box to the left of it and then click the "..." at the right end of the white box.
8 ) Choose the switch you just made and hit "OK"
Everything should work fine. Sorry if it was a tad confusing.